Chemoresistance induction in line cells of the CF41 canine mammary tumour and its relation to PARP and its inhibitor

• Grant number: 19/11360-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: July 01, 2019
• End date: June 30, 2020
• Field of knowledge: Agronomical Sciences - Veterinary Medicine - Animal Pathology
• Principal Investigator: Debora Aparecida Pires de Campos Zuccari
• Grantee: Gabriela Karam Rebolho
• Host Institution: Faculdade de Medicina de São José do Rio Preto (FAMERP). Secretaria de Desenvolvimento Econômico (São Paulo - Estado). São José do Rio Preto , SP, Brazil

Abstract

Breast cancer (BC) is the tumoral type which is more prevalent among women and it has a high mortality rate, due to failure in detecting it early and to the absence of effective markers as well. In dogs, approximately 50% of the mammary tumours are diagnosed as malignant. Thus, the canine mammary tumour (CMT) resembles a great deal with those tumours in humans, which make them excellent models for the study of the cancer biology and therapeutic agents tests. It's known that the chemotherapy protocols which provide an adjuvant treatment in dogs still have limited application and so surgery is yet the most commonly used treatment for these patients. The CMT is characterized by high intra and intertumoral heterogeneity, thus named for the coexistence of different tumoral cell clones which can be formed from their disordered growth with uneven vascularisation, as well as prolonged exposure to the chemotherapy medication which may contribute to the damaged caused to the DNA. The damage is repaired by proteins known as poly (ADP - ribose) polymerase (PARP) that are activated under those conditions. In this case, an innovative alternative is the use of PARP (PARPi) inhibitors as a treatment, since they are already studied for the human breast cancer and can, therefore, contribute to the decrease of the tumour recurrence. This study aims to verify the genetic and protein expression of PARP in canine tumoral line cells (CF41) and the effectiveness of the use of PARPi (Olaparib) in the control and chemo resistant cells. The cells are cultivated and expanded in order to be induced to resistance through the treatment with carboplatin 10 µm for two to three weeks. After the chemoresistance is stablished, the Cellular Viability Assay (MTT) will be done, which will define the dose of the medication for the treatment of the non and the resistant cells. The genetic and protein expression analysis of the PARP from the post-treatment cells will be done through the PCR technique in real time and immunofluorescence respectively. To sum up, the results of this project will be able to confirm the amount of the DNA repair through the PARP on this neoplasia in dogs in addition to elucidate the mechanisms of the BC resistance, besides proposing an efficient treatment for the tumoral recurrence.